RED phase: all admin.test.ts tests fail (404 — routes/mounts not yet created).
Tests cover:
- T-10-08 Pitfall 9: 403 for non-admin on every /api/admin/* route
- T-10-09 Pitfall 7: 400 with no echoed password for all credential failure modes
(PROPFIND/auth failure, createFastmailClient throw, network error, schema mismatch)
- T-10-11: valid credential stores encrypted (AES-256-GCM), not plaintext
- ADMIN-02: PUT /api/admin/calendars/:id/shared — exclusive is_shared=1
- T-10-12 Pitfall 6: POST /api/me/credential ignores body userId, writes to session user
- D-07: non-admin member can POST /api/me/credential (no requireAdmin on self-service)
